52nd Lunar and Conference 2021 (LPI Contrib. No. 2548) 1213.pdf

INITIAL MASTCAM-Z MULTISPECTRAL VISIBLE/NEAR- OBSERVATIONS OF ROVER CALIBRATION TARGETS. J.R. Johnson1, J.F. Bell III2, K.M. Kinch3, J. Kris- tensen3, M. Merusi3, M.B. Madsen3, O.B. Jensen3, J. Joseph4, L. Mehall2, M. Rice5, E. Jensen6, E. Cloutis7, J. I. Núñez1, J. Maki12, R. Wiens8, S. Maurice9, A. Cousin9, P. Beck10, J.A. Manrique11, F. Rull11, 1Johns Hopkins University Ap- plied Physics Laboratory, Laurel, MD 20723, [email protected], 2Arizona State University, 3NBI, Univ. Copenhagen, 4Cornell University, 5Western Washington Univ., 6Malin Space Science Systems, 7University of Winni- peg, Canada, 8Los Alamos National Lab., 9IRAP, Toulouse, France, 10IPAG, Grenoble, France, 11University of Val- ladolid, Spain, 12Jet Propulsion Lab.

Introduction: Directly after landing, the Mars 2020 magnetic dust. The Mastcam-Z secondary calibration rover Perseverance will begin a Surface Operations target is an aluminum shelf carrying seven vertically Transition (SOX) phase, during which initial mounted ceramic color and grayscale chips and seven visible/near-infrared (VISIR) observations will be identical, but horizontally mounted ceramic chips. The acquired of the Mastcam-Z and SuperCam calibration secondary target is intended to augment the calibration- targets by the Mastcam-Z multispectral stereo imaging related information derived from the primary target. system. By the time of the conference, such SuperCam calibration targets. The SuperCam measurements should have been made and will be Calibration Target (SCCT) comprises a suite of 36 compared to laboratory spectra of the targets. targets to be used for calibration of images and to assist Mastcam-Z description. Mastcam-Z [1] includes a with mineral identification, chemometric calculations, pair of focusable, 4:1 zoomable cameras that provide and spectral references to evaluate the health of the broadband red/green/blue and narrowband 440-1020 instrument [5] (Figs. 1,3). The visible diameter of each nm color imaging with of view from 25.6°⨉19.2° target is 8 mm. The SCCT is located at a distance of (26 mm focal length at 283 μrad/pixel) to 6.2°⨉4.6° (110 ~1.56 m from the RSM, such that a Mastcam-Z pixel at mm focal length at 67.7 μrad/pixel). Each Mastcam-Z 26 mm focal length will provide a pixel scale of ~0.44 camera consists of zoom, focus, and filter wheel mech- mm on the SCCT targets. Black, white, red, green, and anisms and a 1648⨉1214 pixel charge-coupled device cyan color samples (shown as targets numbered 1-5 in detector (1600x1200 active pixels) and electronics. The Fig. 5) include the same type of embedded magnets used two Mastcam-Z cameras are mounted with a 24.4 cm by Mastcam-Z (44/11 mm inner/outer diameter). A stereo baseline and 1.65° toe-in on a camera plate ~2 m variety of geologic samples are mainly in the form of above the surface on the rover's Remote Sensing Mast sintered powders [9], seven of which exhibit variable (RSM), which controls azimuth and elevation actuation. VISIR albedos and spectral features of interest that will Calibration. Initial Mastcam-Z SOX imaging will be monitored during the mission. These include a chert verify camera performance such as the pre-flight bias sample with hematite (#8), calcite (#9), ferrosilite (#10), and dark current, multispectral characterization of the orthoclase (“orthose”; #12), clinopyroxene (#13), calibration targets (prior to significant dust accumula- enstatite (#16), and a serpentine-bearing sample (#17). tion), and characterization of the geometric, focus, and Planned observations during SOX. During the first zoom performance of the cameras as a function of object ~25 sols of the mission, pre-planned activities con- distance and camera temperature, including imaging of ducted during SOX include multispectral observations geometric fiducial targets on the rover deck. Mastcam- of the Mastcam-Z and SuperCam calibration targets in Z image calibration will involve conversion to radiance the same scene (e.g., Fig. 1) nominally on Sol 2 and and relative reflectance via use of flat field images and ~Sol 14 (in support of a martian target calibration). observations of the Mastcam-Z calibration targets [1-2]. Multispectral images of the Mastcam-Z targets at a Mastcam-Z calibration targets. Mastcam-Z uses zoom setting of 63 mm will nominally occur on Sol 3. two deck-mounted radiometric calibration targets to Laboratory spectra. Samples of the calibration target validate camera performance, provide an estimate of lo- materials were observed in the laboratory under a cal irradiance, and allow conversion of image data to variety of incidence, emission, and phase angles to units of relative reflectance on a tactical timescale (Figs. provide VISIR spectra for comparison to observations 1-2). The primary target consists of a gold-plated alumi- acquired on Mars. Figures 4 and 5 show lab spectra for num base, eight magnets mounted in the base, eight ce- Mastcam-Z and SuperCam targets of interest, ramic color and grayscale patches mounted over the respectively, at original spectral resolution and magnets, four concentric, ceramic grayscale rings and a convolved to Mastcam-Z bandpasses [10]. central aluminum shadow post (gnomon) painted with Future work. Mastcam-Z multispectral observations an IR-black paint. The magnets are expected to keep the of its calibration targets will be paired with every central area of each patch relatively free of Martian multispectral surface observation to enable calibration 52nd Lunar and Planetary Science Conference 2021 (LPI Contrib. No. 2548) 1213.pdf

to relative reflectance [1-2]. Mastcam-Z multispectral observations of the SuperCam calibration target will be acquired less frequently, mainly to assist in monitoring dust deposition on the targets. SuperCam VISIR reflectance observations of its calibration targets (Fig. 5) will be acquired as the mission proceeds [cf., 6-7] to monitor the stability of the instrument. References: [1] Bell, J, this conf.; Bell, J. Space Sci. Rev., 2021; [2] Kinch, K., Space Sci. Rev, 2020; [3] Wiens, R., Space Sci. Rev., 2021; [4] Maurice, S., Space Sci. Rev., 2021; [5] Manrique, J., Space Sci. Rev., 216, 8 (2020), 1-27; [6] Fouchet, T., this conf.; [7] Wiens, R. et al., this conf.; [8] https://mastcamz.asu.edu/mars-in- full-color/; [9] Cousin, A. in prep, 2021; [10] Hayes, A, Space Sci. Rev., 2021. Figure 3. Schematic diagram showing numbered layout of SuperCam calibration targets [5,9]; cf. Figs. 1,5. Visible portion of targets is 8 mm in diameter.

Figure 4. Laboratory spectra of Mastcam-Z calibration targets (i=0°, e=58°) at full spectral resolution (lines) Figure 1. Portion of Mastcam image acquired during and convolved to Mastcam-Z bandpasses (circles) [1-2]. System Thermal Test showing the calibration targets for SuperCam and Mastcam-Z (primary and secondary) [2] on the Perseverance rover deck.

Figure 2. (a) Mastcam-Z primary radiometric Figure 5. Laboratory spectra of selected SuperCam calibration target. Target base is ~9.8x9.8cm; (b) calibration targets (i=0°, e=30°) at full spectral secondary target is ~8cm long; “shelf” is ~1.6cm wide; resolution (lines) and convolved to Mastcam-Z (c) Inspection photo. (a) Niels Bohr Institute, bandpasses (circles) [3-5]. Numbers correspond to Copenhagen; (b, c) NASA/JPL-Caltech/ASU [8]. SuperCam targets in Fig. 3.